The correct answer is A) To prevent the davits from pulling up against the stops. The upper limit switch is used when raising the lifeboat to automatically stop the davit movement before the lifeboat reaches the top of the davits. This prevents the davits from being pulled up against the mechanical stops, which could potentially cause damage to the davit system. The upper limit switch acts as a safety device to avoid over-raising the lifeboat. The other answer choices are incorrect because: B) is not the primary purpose of the upper limit switch, C) the tricing lines are not directly related to the upper limit switch, and D) the upper limit switch is used to stop the raising, not the lowering, of the lifeboat.